(1) Field of the Invention
The present invention relates generally to an eraser dispenser for selectively extending and retracting an eraser and to a writing instrument equipped with such an eraser dispenser.
(2) Background Information
Writing instruments, such as pencils and pens using erasable ink, are known which are provided with erasers for erasing mistakes, stray marks or other written matter. These writing instruments typically include erasers that are of a short overall length and, therefore, tend to be consumed relatively quickly. Thus there is a frequent need to replace a worn eraser with a new one.
These prior art erasers are generally of two types. One type consists of a relatively short eraser inserted in an eraser cup which is removably inserted in the rear end of the writing instrument. When the eraser becomes worn and needs replacement, the eraser cup is removed from the instrument, the worn eraser is removed from the eraser cup and replaced by a new one, and then the eraser cup is removably inserted back on the writing instrument. One disadvantage of this type eraser unit is that the length of the eraser must be kept relatively short, otherwise the stresses applied by the erasing procedure will break the eraser. Due to the short length of the eraser, it must be frequently replaced. Another disadvantage is that the eraser is continuously exposed at the rear of the writing instrument and is, therefore, susceptible of being easily broken or damaged.
The other type comprises an eraser of relatively long length which is removably held by a slotted metal sleeve. The sleeve is removably inserted into an opening at the rear end of the writing instrument, and the to-be-used portion of the eraser is housed within the rear end of the instrument. When the eraser becomes sufficiently worn, the slotted metal sleeve is removed from the instrument and manually opened so as to permit the eraser to be extended relative to the sleeve. The sleeve is then manually closed and reinserted into the rear end of the instrument. This procedure must be repeated each time the eraser become worn and a new eraser section is needed. Such an eraser unit is disadvantageous because of the manipulations and time required to extend the eraser. In addition, such prior art eraser units suffer the drawback that the eraser is continuously exposed and thus easily susceptible to breakage or damage. If a protective cap is placed over the eraser, the cap must be removed each time the eraser is used which is both troublesome and inconvenient.